Conventionally, an X-ray computed tomography apparatus and an X-ray diagnostic apparatus remain active as when they perform X-ray computed tomography and X-ray diagnosis, even in a standby mode during which they do not perform X-ray computed tomography and X-ray diagnosis, in order to accept urgent patients at any time (see FIG. 7). This poses a problem that the power consumption is large in the standby mode during which the apparatuses do not perform X-ray computed tomography and X-ray diagnosis.